Pneumatic hammer.



FJM. FABERL PNEUMAnc HAMMER.

APPLICATION FILED SEPT. 2 1915..

Patented Nov. 21, 1916.

/nalelzo F1111# M ber Per* FRANK' 1v1.I FABER, QF'UANTON, .01nd

PNEUMATIC HAMMER,

of the valve block; 36 a series of annular ports in the valveblock which open into the groove 38 through the radial ports SET.

are rearward continuations of the ports 36 and communicate with the periphery of the valve block through the radial ports 40.

is a series of longitudinal ports in the cylinder which register with ports tl in the valve block and which enter the bore in the cylinder llt 3l. Ports 2l and 3U are held in register with ports 21" and b5, respectively, by lneans'of the dowel pin 4l.

24; is an annular roove in the periphery of the valve block w iich comnmnicates with the interior of the block through the series of ports* 25.

The handle and cylinder are secured together by means of the threaded parts 58; the threads also-perform the function of forcing the handle against the thinible at the neatly finished surface 1b and also of forcing the thimble against the valve block at the'neatly finished surfaces T and also of forcing the valve block against the cylinder at the neatly finished surfaces 29. The fits at the surfaces l7 7 andv 29, are sufficiently close to prevent leakage.

The interior of the valve 13 is formed Vto foar coaxial diameters which make close sliding fits on the various outside diameters, H, I, J and K of the valve block; while the end periphery of the valve toward the right makes a close sliding fit in the diameter' M in the valve thimble.

5G is an annular groove on the interior of the valve, 57 is an annular groove on the pe riphery of the valve, and are a series of small radial ports connecting the grooves 56 and 57.

48 is an annular groove on the interior of the valve, and 47 is a. series of radial ports through the wall of the valve and into the groove 48.

50 is a shoulder on the valve which' abats against the valve thilnble 7 when the valve is in the position shown in Fig. 2.

19 is a series of holes through the shoul- .der 50.

'2 3 is a. radial surface on the valve, due to the difference in diameters J and K.

22 is a lip on the valve, whose interior closely 'lits diameter K on the valve block.

V17 is-a radial surface on the valve, due to the4 difference in diameters I and J.

A1l is a radial surface on the valvexdues to the difference in diameters H and I.

39 is a groove on the interior of the valve. Y

39* isa series of openings through the wall of the 'naive into the groove 39.

11 iso" annular chamber in the valve thilnbleadapted to be closedrby the valve and valve block. .i .V

15 is an annular chamber between the 4verona nut loch) valve and valve block, due to the differences in dian'ieters l-l and l and which 1ua be '.rnlai-ged by groovingr thc interior of the valve as shown.

1S is an annular chamber between the valve und valve block, due to the dilfcrenres in diameters I and J.A

The rear end of the cylinder is boredto closely fit the outside of the thimble at J-lr.

2B is an open space between the c vlinder and the valve, and communicates with the atniosphere through a scriesof ports 2T.

On the outside of the cylinder are formed a number of teeth 42.

45 is a dogr having teeth 45 which mesh into the teeth 42. The dog l5 is litted'into a recess in the handle 1, as shown in Figs. l and l) and is held in place by the screw 42'3.

4G isa hole in the screw 43, through which a split pin may be inserted lo prevent the screw from turning.

44 is a washer of yielding'material (preferably sach as the wellltnown and so called which `holds the dog against the handle under tension` to prevent movement and consequent wear on the teeth -lJl and 45, whemthe hammer is in operation` The function'ol the dog is to lock the handle to and prevent itsv unscrtuving from the cylinder.

The operation of my device is azf follows: Fluid pressure is admitted to the annular chamber 3, through the main :ulu'iission port 2,l and enters the annulargroovc ll) through the series of ports` S: pressure also enters the annular chamber 15, betwe'en'the valve and thel block7 through the ports '1) aml lli; consequently the inside of the valve. Idock and cylinder and the annular chamber 15 are under pressure when the throttle valvl.` (not shown) is open. At the beginning of the forward stroke, the valve beiner in its for- -ward position as shown inlfig. 1. the piston 32 will be at, or near.` theextremel rear end ofthe cylinder bore1 preferably about 1/2 from the handle, which formsthe rear cylinder headg' when the valve is'in itsl forward position. flaidpressure enteringthrough the Small orifice G moves thc piston forward, in the direction indicated by the arrow, untilit 'passes the series of ports 512, when fluid pressure passinlf.,r from the groove 10 into the chamber 1l, thence through ports 12, into the cylinder bore.y forces the piston forward athigh velocity. As the piston moves for* ward the fluid in the frontend of the. c vlinder exhausts through ports 34. 35 3G and 37 into Vthe groove 38 and thence through thel holes 39 into the chamber 2li and thence to the atmosphere through. the openings 27. Thenpressare acting onthe radial surface 1 3 of the valve is thus tending to hold the valve in its forward position, there is au opposin.rr pressure on the smaller annular surface 14, but whichis not sufficient to overi5." Widen,-

come -the force acting iigiiiiistlih.4 When thev piston on its 'forward Stroke passes the' ports 25, pressure is vadmitted to tbe' groove .24,- :ind riots :igiiinet theannuliir surface 23, which tends to force the valve' rearwardly,

The -rediil' surfzioes. '13?, lil, 17 and 23; are

so proportioned that 'tglie combined areas .of the radial surfaces ll'iiiid 23 are less than j the radial surface 13", Consequently' the lo .valve will remain in tlie .position shown in Fig. l after the piston li'iispessed beyond ports 25, and' I'nessiireiidmited 'against the' rejdielisi'irfooe 23.: .X-Tlien'tlie relire'- iii'is 2id- .vanced beyond 'opening 30,' .pr ess\ 1re is. .ad-

mitted 'to'tl'ie ehiiinber'18', tlirouglig the ports 1212.1, 2l and 20, which.zitsiii'giii'nst the rigidi-al "35 pressure r sainet" e' the is seal eliiiinber, iisindiuted .in Fig. 2, While pressure 'from the oliiiinberll: enters, tlie lirougli' ports. 4 0, j

Ii0 frontend of the cylinder the piston. rear'- 'f'wardly, o r 'in tliedirertioh; indicated by tlie i ari-low infFg, 2 When tlieve r'kes tlie 'attendent-.yto rebound severaltimes' were not. ineens proviierl to -prevent this zi,c t i on. In

-earlier experimt I ''oiind that this repressure 'builds 1ip on tlie: remend ofi Aoo ine'sthe 'Constant 'pressii'reon the u nn'iiliir .surfiioe il; the valve ieeonseriueiitly.thrown portio'ned that? the combined Areesbf the the' valve willl lt: oit' from eqrninimieitiqii 'with the flu-essuie iid .piston :oevers the ports 2 5, tli.e' liiiid 'in -tl'ie reiii` end of tlieoylinder "is compressed o 'r'id against the siiifjfiioe'"l3" the indre, i'intil' it '-oife'r- 70 iiitoftlie position..Shown" i1i Fig. l and tfl ie )2nite-.irre so proportioned tliattlie vulve jill betlirown forward 11i time to admit pres- -75 sure to tlie'r'ear end ofthe cyliiiderlinti'ine to eetcli the piston beforeit strikestlie4 rear cylinder -lieiid, Fluid pressure is admitted 1to'tlre cylinderl bore thro'u'gli foi-' tl'ie pii'i-, vpose of-[assisting the not of ooiiipression. Ji'iet' 80 .de eoiibed, andtlins throwing the vulve more quielclj,1 tliiin would be done 'by siinply' oompl'essingthe l'uid inthe reir end of tlieoyl 'in der. -Theoyr-.le of operations is tliiis coinpleted 'and is repented iiizriipid siieoession. 'g5

The lip'QZon tlie forward end of the vii-l ve opening exliiiiist fron-i groove 2 4 giving wlizitibg is known, ne hip .in steiin'i engine practice. vThe n divimtzigeof this liip is two fold. l.It

insuresV the positive closingl oLt n d ini ssjioii 'port 10' before 'exhaust operisfioiiigr it' 24, 1

. i'eeiiwiii'd] :piisses port 30," .fluid pressur 'i105 'forcing' the' pieton re'iiri-riiidlyf ente ports tain parts of the valve and valve block ot pneumatic tools of this class will seriously interfere with the operation of the tool. For example-when the valve is in the position shown in Fig. :2, leakage passing from the groove 10 and between the valve and thilnble, might enter the chamber 11 and pass thence through ports 12. into the rear end ot' the cylinder. with the result that after the piston passes ports on its rearw ward stroke. com pression will build up more rapidly than desirable and stop the piston before it has reached the proper limit on its rearwardstroke. thus shortening the piston stroke. and correspondingly reducing the force ot' its blow. In order to prevent this lealv'age from entering' the rear end ot the cylinder, I provide the arrangement shown in detail in Fie. 11. consisting of the annular groove al, the small ports M. a groove 53, the small ports groove 5T and a series of small holes 4E) in the valve. lith this arrangenunit, leakage Jrom the groove 10 in the thimble. will. instead of passing into the rear end of the cylinder. enter the `groove and pass thence through ways 54. 525. 52, 5T. 51 and 4%) into the space QG and thence into the atmosphere through the ports 2.

lVhen the valve is in the position shown in Fig. 1 ports 52 are sealed by the close fit of the valve in the thimble at 13". thus preventing wasteful leakage from chamber 11 through 5l, :i3 andI 52. Pressure from the chamber 15 is prevented from leaking into ports 12 by the groove 56, from which such leakage passes through the small pmt-s into the groove 57 and thence through 4!) to the atmosphere as before. By thus preventing leakage from entering the rear end of thecylinde 'fa constant length of stroke is insured.

When the pistou covers port 30, on its forward stroke, the valve (being` Vin position shown in Fig. l), mightbe thrown prematurely by leakage. from constant pressure chamber 15 into chamber 1B, thus admitting pressure aga-inst the radial surface 17. To prevent such action I provide the groove 4S in the interior ofthe valve and the. openings 11". which A'are in constant communication with the atmosphere by way of't'ne chamber 9.6 and ports 27. By this arrangement whatever leakage may pass from constant pressure chamber 15 toward chamber 1S is shunted to the atmosphere. I also prevent leakage from passingl from groove (which is under pressure when the valve is in position'shown in Fig. 9.), into the chamber 18, by the groove 39 in th valve, which permits leakage from 38 to pass through the series of holes 39* in the valve, into chamber 26 and thence through exhaust ports 27. For convenience I will hereinafter refer to the grooves 39, 48, 56 57 and 54 and the portions of the block contiguous thereto, as leakage zones. while I will refer to the portions of the valve and valve block which are subject to fluid pressure, either constantly or intermittently, as pressure zones.

It is evident that when the valve moves from the position shown in Fig. 2 to that in Fig. 1 the lluid in the chamber 18 would be con'lpressed. were it not allowed to esf cape through'ports 2U. 2l and P30. a condition which occurs in certain 'sizes of hammers, wherein the piston is so long that it fails to uncover the port 5l() when at the extreme end of its rearward stroke. A perfectly fitting valve under'the'sc conditions would not be moved to the extra-ne forward position, as shown in Fig. 1f bythe pressure on 13b, which would seriously interfere with the ollieration ot' the device: l therefore provide one or more small leakage holes 19, to prevent'compression taking place in this way; the leakage holes 15). bein,"7 so small relatively to the size of the ports'ltl. 31", 21 and 20, as not to interfere with the action of the air against thel radial surface 1T to throw the valve. after the piston has passed port 30 when movingr forwardly.

In pneumatic hannners of this general dcsign the piston' and snap are thrown into violent vibration 'atthe instant'ot contact, with 'the result that the cylinder bore is worn and enlarge-d atthe front end. as indicated in dotted lines 32".' as is also the fit of the snap in the cylinder. The insulting leakage due to such cylinder wear of fluid pressure admitted throughports 10. 3G, and 3l for drivin,"y the piston rearwardly, becomes. in time. so great as to seriously impair the efficiency of the tool. It is common practice to remedy this condition by heating the cylinder and closing,r in the worn )art under a hanuner and then reamin T the cylinder bore and the `part ot the cylinder wherein the snap is-inserted. to the proper size. In order that this operation of re-reaming may be performed repeatedly.- it is desirable that the thickness of metal between ports 35 and the cylinder bore 1w as great, as practicable: while in order to reduce weight, all dil'nensinns of tools of this class are made assmall` as lassible. consistentv with proper strength. l consequently make the diameter K. ont-the valve block, such that the inside edges of ports 3G- are quite close to the c v'linderbore at; the point 36", and drill the port 35 at an vangle to the axis of the cylinder bore. tl us acquiring a suli-. cient thickness of metal between port 35 and the cylinder bore at the front end to permit of drawing in and reboring the cylinderv a number of times.

I claim:

1. In a pneumatic hammer a valve having a first radial surfaceV subject to constant pressure tending to throw the valve in a certainl direction, a second radial surface subject to intermittent pressure tending to thro7 the valve in the same direction, a third radial surface subject to intermittent pressure tending' to throw the valve in the saine direction, and a fourth radial surface subject tonintermittent pressure tending to throw the'I valve 'in the opposite direction; the areaof the fourth radial surface being greater than the sum of. the first and second radial surfaces, but less than the sum of the first, second and third radial surfaces.

V2. Inv a pneumatic hammer. a valve having a radial surface under constant pressure, a second lradial surface under pressure intermittently admitted from the cylinder bore, a third radial surface underl pressure intermittently 'admitted from the cylinder bore, all of said pressures tending to force 'the valve in one direction, and a fourth radial surface' under pressure intermittently admitted from the main supply tending to force the valve in the opposite direction; the area of' said fourth radial. surface being lesszthan the combined areas of the other three.

8. In a pneumatic hammer a Valve having a radial surface subject to constant pressure and. a second radial surface subject to pressure intermittently admitted from the cylinder bore of the hammer, said pressures tending toA force the valve in one direction, and a third radial surface, subject to pressure intermittently admitted through the main supply and tending to force the valve in the opposite direction, said third surface being greater than the combined areas of the other tivo;l

Ll.-In a pneumatic tool a valveblock,`a valve .slidingly fitting the exterior ci the valve block, a thimble tting the peripheral exterior of the valveblock and also the periphera-l exterior of the valve, a port in the thinible to which fluid pressure is constantly admitted While the tool is in operation, said lport'being'sealed by the valve `when the valve is at one end of its stroke, and being fopen to communication with the interior of the cylinder when thevalve is at the other 5. In a pneumatic tool a cylinder, a valve block, having-"its interior Vof the same diA block having four dia-meters on its exterior and a valve having four diameters on its mterior said diametersv 1n -valve corresponding-to and slidingly fitting-the exterior dij" ameters of the valve block.'

G. In a A neumatic tool a cylindeaf`hol-l I.

low valve 'lock' secured' in axial aliiiement with the cylinder boie, `a' piston slidingly fittin the hol ow interior of the valve block and t e cylin erbore, a valve slidingly lit ting four diameters on the exteriorof the valve block, and a thirnble slidingly fitting'- a portion exterior of the valve. l

7. In a pneumatic tool a valve blockA hav ing four diameters, a valve having four cor-4 responding Aand shdingly fitting diametersi said valve having four radial surfaces, iui pressure acting constantly -on one of said radial surfaces and intermittently on the other' said radial-surfaces.

8. In a pneumaticrtool a valve block having `four"diameters on itsi exterior and avalve havingfur diameters on its interior-1*? said diameters on valve, corresponding to,4 and slidingly fitting said diameters on the valve block.

9. In a pneumatic tool. a valve having opposing radial pressure areas, a valve block .A

sli'dingly fitting the valve, a' leakage Vzone on the valve and block and a pressure zone en the valve intermittently subject to pres.- sure and adjacent to seid leakage zone. Y

10. In a pneumatic tool a valve bloek,'a

l2'. In a pneumatic tool a cylindeifhavinglf one or more longitudinalports 'in the -ivall of the cylinder, said port or ports being farther from the cylinder-'bore at the'forward `end o f the cylinder than at the rearward end.

' 13. In a pneuma'ztictool a cylinder having a cyl-inder'bo're', a longitudinal' port in the wall of the cylinder, the axis of said port'bewing at an angle to theaxis'o the cylinder bore, said angle being such that the thickness of wall between the cylinder bore and port is greater at theA frontend than at the rear end of the cylinder.

raamt,M.. FABER. 

